Skip navigation

Chorionic villus sampling - series

Normal anatomy

Normal anatomy

Chorionic villi are microscopic projections that line the chorion, the outermost layer of the embryonic sac. Surgeons sample these projections for genetic testing because they contain the same genetic material as a fetus.

If you are at risk for delivering a baby with genetic abnormalities, your health-care provider may recommend this prenatal test, which is performed at 10 to 12 weeks gestation to find out a fetus' genetic makeup.

Update Date: 8/7/2012

Updated by: A.D.A.M. Health Solutions, Ebix Inc., Editorial Team: David Zieve, MD, MHA, and David R. Eltz. Previously reviewed by Linda J. Vorvick, MD, Medical Director and Director of Didactic Curriculum, MEDEX Northwest Division of Physician Assistant Studies, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington. Susan Storck, MD, FACOG, Chief, Eastside Department of Obstetrics and Gynecology, Group Health Cooperative of Puget Sound, Bellevue, Washington; Clinical Teaching Faculty, Department of Obstetrics and Gynecology, University of Washington School of Medicine (5/31/2012)

Related MedlinePlus Page

A.D.A.M Quality Logo

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org). URAC's accreditation program is an independent audit to verify that A.D.A.M. follows rigorous standards of quality and accountability. A.D.A.M. is among the first to achieve this important distinction for online health information and services. Learn more about A.D.A.M.'s editorial policy, editorial process and privacy policy. A.D.A.M. is also a founding member of Hi-Ethics and subscribes to the principles of the Health on the Net Foundation (www.hon.ch).

The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions. Call 911 for all medical emergencies. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. Copyright 1997-2014, A.D.A.M., Inc. Duplication for commercial use must be authorized in writing by ADAM Health Solutions.

A.D.A.M Logo